Survival of Botrytis cinerea in southeastern Spanish greenhouses

The relative importance of sclerotia and mycelia of Botrytis cinerea Pers e x Fr. as structures of survival in southeastern Spanish greenhouses was inv estigated. Sclerotia were not found in the SE region, neither on plant debr is nor on living plant material, suggesting it may serve only a minor role in epidemic development. B. cinerea survived mostly as mycelium. The percen tage of artificially inoculated tomato stem pieces from which mycelium was recovered, was used to quantify its survival rate. Outside the greenhouses, mycelium survived in 33% and 5% of the tomato stem pieces 110 days after i noculation in 1995 and 1997, respectively. After the same number of days in side the greenhouses, no mycelium was recovered from stem pieces in 1995, a nd in 1997 only 7% of the stem pieces contained mycelium. Survival of mycel ium outside and inside the greenhouses was significantly (P < 0.05) differe nt after 47, 83, and 110 days of exposure to field conditions in 1995, but they were not different in 1997. Under controlled conditions, mycelium of B . cinerea lost viability at 100% relative humidity at temperatures ranging from 5 to 40 degreesC, suggesting that air temperature and relative humidit y accounted for loss of viability of mycelium.